The invention relates to insulation retrofit for exterior walls, or construction of walls for new houses or buildings, in particular, low-cost insulation using readily available materials which can be assembled on-site. Very low cost sustainable insulation materials and systems are needed for certain applications, such as improving the energy efficiency and comfort levels of houses. These insulations would be based on locally available materials that require a minimum of physical or chemical processing to make them useable and could rely on unskilled labor for installation. This technology solves the problem of insulating existing houses with solid walls, such as those constructed of adobe, stone, masonry or logs. Such houses exist in Alaska, the Southwest and in many other parts of the world, and they are difficult and expensive to insulate using conventional methods. The technology was demonstrated by using pumice, flyash and sawdust as the insulating material. Much of the prior art pertains to factory made articles which are not assembled on-site from readily available materials.
Bulk loose fill natural, manufactured, and recycled resource-efficient materials such as pumice, flyash, bottom ash, sawdust, shredded leaves, peat moss, expanded clays and shales, vermiculite, and perlite have moderate insulation values and are locally available in many areas. Use of such materials provides a means to retrofit exterior wall insulation or construct energy efficient walls for new buildings, at minimal cost. A problem is that the loose fill material must be used without mixing it with portland cement otherwise it loses the insulating value. For example, pumice is a naturally occurring, lightweight volcanic ash that has a moderate thermal resistivity. However, when pumice is mixed with portland cement to make masonry units or concrete, it loses over 90% of its thermal resistance. Therefore, it is important to use the material alone as a dry loose fill material, as this invention does. For retrofit, blowing or mechanically conveying bulk loose-fill material into a long, woven fabric tube layered upon itself against the exterior wall enables the insulating structure to conform to uneven wall and ground surfaces. Insulation members such as those described in U.S. Pat. No. 3,979,870 utilize low cost insulation materials but are not readily assembled on-site and are rigid and thus do not conform to uneven surfaces. For new construction, a wall is constructed according to the present invention by blowing bulk loose-fill material into a long, woven fabric tube layered upon itself.